2006-10-17 04:00:00 PDT Washington -- Despite the surge of women into the workforce, mothers are spending at least as much time with their children as they did 40 years ago, and the amount of child care and housework performed by fathers has sharply increased, researchers say in a new study.

"We might have expected mothers to curtail the time spent caring for their children, but they do not seem to have done so," said one of the researchers, Suzanne Bianchi, chairwoman of the department of sociology at the University of Maryland. "They certainly did curtail the time they spent on housework."

The researchers found that "women still do twice as much housework and child care as men" in two-parent families. But they said total hours of work by mothers and fathers were roughly equal, when they counted paid and unpaid work. Using this measure, the researchers found "remarkable gender equality in total workloads," averaging nearly 65 hours a week.

At first, the authors say, "it seems reasonable to expect that parental investment in child-rearing would have declined" since 1965, when 60 percent of all children lived in families with a breadwinner father and a stay-at-home mother. Only about 30 percent of children now live in such families.

With more mothers in paid jobs, many policymakers have assumed that parents must have less time to interact with their children. But the researchers say the conventional wisdom is not borne out by the data they collected from families asked to account for their time. The researchers found, to their surprise, that married and single parents spent more time teaching, playing with and caring for their children than parents did 40 years ago.

For married mothers, the time spent on child care activities increased to an average of 12.9 hours a week in 2000, from 10.6 hours in 1965. For married fathers, the time spent on child care more than doubled, to 6.5 hours a week, from 2.6 hours. Single mothers reported spending 11.8 hours a week on child care, up from 7.5 hours in 1965.

"As the hours of paid work went up for mothers, their hours of housework declined," said Bianchi. "It was almost a one-for-one trade."

Fathers have picked up some of the slack. Married fathers are spending more time on housework: an average of 9.7 hours a week in 2000, up from 4.4 hours in 1965. That increase was more than offset by the decline in time devoted to housework by married mothers: 19.4 hours a week in 2000, down from 34.5 hours in 1965.

Rather than relying on anecdotes and images in the mass media, the researchers used "time diaries" to measure how families spent their time. Using a standard set of questions, interviewers asked thousands of parents to chronicle all their activities.